The gold foil experiment was an experiment to see if atoms consisted of mostly empty space.

It was conducted by Ernest Rutherford in 1908. It was conducted by firing alpha particles that were positively charged through gold foil surounded with a reflecting screen.

The results were successful and it proved that atoms were mostly empty space with a very tiny, positively charged nucleus at the very center of the atom.

The theory of relativity was a theory created by Albert Einstein in 1905 and 1915.

His theory has two serperate physic theories which are special relativity and general relativity.

What is Special relativity?

Special relativity is a theory about how speed affects mass, time and etc. It includes time dilation, length contration, mass-energy equivalence, relativistic mass and relativity of simultaneity.

What is General relativity?

General relativity is how gravity is not a force, but how massive objects cause a distoration of spacetime by making a curvature.